1. Field of the Invention
The present invention relates to materials for producing electromagnetic shielding members surrounding electromagnetic-wave generating equipment, electronic equipment which is sensitive to external electromagnetic waves, or the like.
2. Prior Art
Up to now, in electrical communication equipment and the like, housings thereof have been made of metals with a character of electromagnetic shielding in order to prevent wrong operations due to external electromagnetic waves. However, it is not only difficult to construct such shields but it also brings a weight increase to mold a complicated-shaped member out of metal. Consequently, various methods for adding a character of electromagnetic shielding to easily molded plastic materials have been proposed.
One of such composites with a character of electromagnetic shielding is a composite material made by mixing with a conductive fiber or a conductive powder with a plastic, and, for example, in Japanese Patent Preliminary Publication No. Hei 2-213002 is disclosed a composite, wherein metal conductive fibers coated by low melting point metals are included and dispersed in a thermoplastic synthetic resin.
The injection molding of this material can produce molded articles with an appropriate conductivity, because the conductive fibers dispersed in their molded bodies are constructed such that the fibers are fusion-bonded to each other by means of the low melting point metal coating thereon. But, though such molded articles have a sufficient effect of electromagnetic shielding in a low-frequency range, they have a drawback of an insufficient shielding in a high-frequency range.